Hydrocarbon vapor emissions from an engine air intake system of a vehicle may be captured in adsorbing systems.
Example devices adsorb these hydrocarbons when the engine is shut off. The hydrocarbons are desorbed and burned in the engine when the engine is operating. Hydrocarbon loading and purging cycles may continue throughout the useful life of the vehicle. Some devices impose flow restrictions in the air intake to provide sufficient adsorption, while others do not. Some systems utilize various extra valves and/or ducts to open/close and/or expose adsorbing elements only under selected conditions.
However the inventors herein have recognized a number of issues with such approaches. For example, some systems may unacceptably increase air flow restrictions in order to provide sufficient hydrocarbon adsorption. Further still, operators may tamper with flow restricting components by removing the adsorber components without the removal being obvious. As yet another example, there may be issues related to degradation of mechanical actuation to close and/or open air intake system components, possibly resulting in unintentional increased airflow restrictions, or both.
Thus in one approach, a hydrocarbon adsorbing arrangement for an internal combustion engine is provided. The hydrocarbon adsorbing arrangement may include an air intake tube having a cross-sectional shape and configured within the engine. An internal structural element may be positioned within the air intake tube and may be configured to support the cross-sectional shape. A hydrocarbon adsorber may be disposed adjacent the internal structural element wherein a fluid containing hydrocarbons passing through the air intake tube can make contact with the hydrocarbon adsorber. This approach provides various options for placing the adsorber within the intake package, resulting in superior purging because the adsorber can be directly adjacent to the engine air flow, and reduces impact on flow restriction (horsepower loss).
In one particular aspect, the internal structural element may retain carbon coated paper within the air intake tube, yet expose the carbon coated paper via cut-outs, or windows in the internal structure. In this way, the structural element, which may be a plastic insert, can not only maintain the cross section of a flexible clean air tube open during high air flow and high heat operating conditions, but also function to collect hydrocarbons during at least engine-off conditions.
It should be appreciated that the internal structural element may be in various forms. As noted, it may be a plastic insert. Also, the structural element may retain the hydrocarbon adsorber between itself and the inner wall of the air intake tube. Alternatively, the adsorber may be adhered to the inner wall of the structural element. Finally, the structural element may include various internal and external cages or shells, where the cages and/or shells retain the adsorber, and where the structural element is inserted and retained within the clean air tube
It should also be appreciated that with such an approach the flow of air to the engine combustion chamber may depend on the presence of the hydrocarbon adsorber, so that if the hydrocarbon adsorber is disturbed or removed by a customer, engine performance may be affected by deformation of the elastic tube.